Apparatus for simultaneously polishing both faces of a travelling strip of glass



APH] 29, 194? F. B. WALDR APPARATUS F SIMULTANEOUS P ISHING'BOT O. TRVELLING` S P OF GLASS Filed April 9 1946 2,419,926 H PACI-:s Y

Patented Apr. 29, 1947 UNITED sTATEs 2,419,926 APPARATUS FOR sIMULTANEoUsLY AroL- ISHING BOTH FACES OF A STRIP OF GLASS TRAVELLING Frederic Barnes Waldron; Prescot, England, assignor to Pilkington Brothers Limited, Liverpool, England, a British company Application April 9, 1946, Serial No. 660,743

In Great Britain September13, 1944 3 claims.

This invention relates to apparatus for simultaneously polishing bothfaces of a travelling strip of glass. f

Such form of apparatus commonly comprises polishing tools adapted to operate on the underface of the glassstrip, whilst at the same time they serve to support the strip, each such tool lncluding a plurality of polishing pads each adapted to turn on a substantially vertical axis, the tool being mounted on a frame which is adapted to rotate so as to bring each pad to an edge of the glass.

The tool may either be supported on a single frame with central driven shaft or may be supported on a plurality of sub-frames in turn supported on a main frame with central driven shaft, each sub-frame (if used) being free to rotate on lts support on the main frame. Each tool is provided with means of vertical adjustment, whereby the strip of glass supported by the plurality of tools can be kept free of bends in passing through the apparatus.

Polishing is effected by the rubbing of the pads over the glass, while rouge and water is supplied either to the pads or to the glass. After a :ertain time of operation, rougie becomes c'aked an the pads to form a hard layer, in which foreign matter such as glass splinters may be emaedded, and the polishing action is then impaired.`

lhe pads then have to be cleaned by removing the aard layer and, to effect this, access must be ob- '.ained to the operative surface of the pads. Fur- ;her, the pad vcoverings gradually wear and may iecome damaged and then the covering must be removed and replaced.

If a polishing tool operating on the undersuris the remaining pads with partially worn cover ngs. This has the result of imposing bending tresses on the glass which may be sufficient to reak the glass.

'I'he main objects of the invention are to proide mechanism in apparatus for simultaneously olishing both faces of a travelling strip of glass 2 Y by which each individual pad can'be dropped sufciently away fromthe glass so that the felt can be readily changed and scraped when necessary, and can then be returned to operativesposition without disturbing the pristineadjustment of thev pad while the remaining pads remain in operative position supportingvthe glass and by which each pad can be individually and accurately adjusted in height so that all the pads of the tool can be brought'into one plane and mutuallysupport theglass whether they are new or worn.

In accordance with the presentjnvention apparatus for polishing the undersurface of a horizontal travelling strip of glass comprising a 'polishing tool in which a pluralityvof polishing pads,- each. adapted to turn on a vertical axis, `is supported on a frame fadapted to rotate on a vertical axis, ls characterized by two independent means for moving each pad vertically, one adapted to drop the pad vertically sufficiently far from the glass to give ready access to its operative surface'and to return it to its previous position without disturbing the adjustment, while the other pads remain in operative position supporting the glass, and the other adapted to give nal adjustment of the pad accurately vinto the plane in which the other pads support the glass.

In a preferred constructionv according to the inventioneach pad is rotatably supported in a sleeve, which sleeve is verticallyY slidable Vin a tubular member carried by 'the tool, a horizontal shaft mounted on the tool and passing through said tubular member, means mounted on the shaft for raising the sleeve to an upper position or permitting it to be dropped vertically to ay lower position, an extensible connection between said raising means and said sleeve disposed axially of the sleeve and in threaded engagement therewith and means for actuating the extensible connection to achieve fine adjustment of the pad in raised position comprising vertical teeth on said extensible connection, a pinion engaging said teeth and means for rotating said pinion, said vertical teeth being long enough to retain engagement with the pinion during vertical movement of the sleeve.

The sleeve raising means may comprise a. crank shaft journalled inthe tubular member attached to the tool, with a block on a rod connected to a crank-pin of the crank shaft supporting the extensible member.

3 extends from the hub. The position of the free end of the bi-rnetal 40 can beadjusted by rotating a cam 43, as the lever 4| is continually urged against the periphery of the cam by a spring 44. An electric heating element 45 is carried on the end of the bi-metal strip and is insulated from the strip. The heater element is a low voltage type and is energized by a step-down transformer 41. The primary winding 48 of the transformer is connected to the usual 110 volt household power lines 49 and 50 by wires 5| and 52. The secondary winding 53 of the transformer is connected to the heating element by wires 54 and ,55. The heating element 46' is arranged to be'moved by deflection of the bi-metat intermediate juncthan those of junctions 18 and 15 o'r they may vanometer is connected inseries with the thermocouples 80 and 68 through the terminals B5 .and 18. l

tions 58 and 59 of a thermo`couple indicated generally at 60,' so that these junctions areheated above atmospheric temperatures preferably by radiant heat. The thermocouple 60 comprises a U shaped constantan wire 6| having the ends thereof joined with copper wires 62 and 63 at Stand 59. The Wire 6| is preferably shielded from the heat of the heater 46 except at the junctions 58 and 59. The circuit foi-.the thermocouple E8 includes a galvanometer 61 and a thermopile 88, which latter comprises the device 36. The wire E2 is connected to the thermopile 88 at a junction 10 andthe wire 63 is connected with a terminal 66 of the galvanometer.

The 1ever4| is adjusted by the cam so that when tween the junctions 58 and 59 and each junction is subjected to the same intensity of radiant heat,

and therefore, the temperatures of these Junctions willbe substantially the same. It is to be understood, however, that the lever 4| couldbe adjusted b`y the cam so that theheater element would be midwaybeiween thejunctions of the thermocouple at other temperaturesthan "I2" F. As the temperature of the birnetal decreases, the heater element 46 is movedtoward the junction 59 for increasing the intensity of the radiant heat at that junction while causing a decrease in the intensity of the .heat at vthe junction 58. This increases and decreases the temperatures of the junctions 59 and 58, respectively. When the temperature of the bimetal is raised above 72 F., the heater element isv moved nearer to the junction 58 and that junction becomes warmer than the junction 59., Thus, ona decrease in temperature of the bimetal below 72 F. an electric potential will be established tending to causea iiow of current through the thermocouple circuit from wire 6| to wire 63, and on an increase in temperature above 72 F., the iiow of current or potential will be established in the opposite direction. When the heater element isV exactly intermediate the junctions, both junctions are heated equally and no current will `be generated.

The junction10 of thermopile 58 -is connected with a constantan wire `1|'. Thek opposite end of the wire 1| Ais joined with one end of a copper wire 12 at junction13 and the opposite end of the wire 12 is connected to a constantan wire 14 at junction 15. e The opposite end of the wire 14 is connected to a copper wire 16 at junction 11. The junctions 10 and 15 are each in close heat exchange relation with a mass of heat absorbing material 19, such as copper. so that the temperatures of the wires at these junctions will lag with respect to changes in ambient temperature.

close heat exchange relation with masses smaller The junctions 13 and 11 are each in- It will be apparent that when the temperature of the air in the bonnet increases, the temperatures of the junctions 18 and 11 of the thermopile will increase more rapidly than the temperatures of the junctions 10 and 15 and, therefore, an electric current will be established in wire 18 tending to flow toward the coil 80. When the temperature of the air in the bonnet decreases, the thermopile 68 will establish an electric current tending to flow in the opposite direction since the junctions 13 and 11 will be cooler than junctions 10 and 15. When the temperature of the air in the bonnet of the furnace is constant or substantially constant, the junctions of the thermopile 68V will be at the same temperatures,

and therefore, no potential/will be established by it. Thus, the thermopile establishes an electricA potential proportional to the yrate of change in temperature, Aand thedirection of iiow of cur-- rent is dependent 'on whether the temperature is i increasing or decreasing.

It will be noted thatthe thermocouple 84 and y thermopile 68 establish currents of the same polarity, or augment one another,` whenever the` temperature of the bimetal 40 is aboveor below 72 F., and the air in the furnace bonnet is increasing or decreasing, respectively, and that potentials are established counterI to one anothei whenever the temperature of the bixrietal` 40 is aboveor below 72 F., whilethe temperature of the air in the furnace bonnet is decreasing or increasing, respectively. Y

The galvanometer 61, a top plan view of which is shown diagrammatically in Fig. 2, is constructed so that when the potential at the terminal 66 of the galvanometer 61 is greater than the potential at the terminal 18, the coil Il will be deiiected in a counter-clockwise direction, for example, and when the potential at 18 is greater than at 66, the coil will be deflected in a clockwise direction. When the potentials are exactly the same or zero, the coil will be in the position shown in Fig. 2. It is apparent that the galvanometer is responsive to the algebraic sum of the potentials established by the thermopile and thermocouple.

An armature 8|, which is mounted on a vertical pivotv 82, is oscillated by movement ot the coil 80, and this armature carries an iron armature 83 and a contact bar 84.

Two suitable electromagnets, shown diagrammatically at 85 and 86, are arranged on opposite sides of the armature 83 and are equally distant 49 by a circuit including a wire 9|, time switch f 92 and wire 93. The time switch 92includes a contact'bar I The coil 8l iscon- 3. Apparatus according to claim 1 characterized by, each pad being rotatably supported in a. sleeve, which sleeve is vertically slidable in a tubular member carried by the frame, a horizontal shaftV mounted on the tubular member and passing through said tubular member, means mounted on the shaft for raising the sleeve to an upper position or permitting it to be dropped vertically to a lower position, an extensible connection between said raising means and said sleeve disposed axially of the sleeve and in threaded engagement therewith and means for actuating the extensible connection to achieve fine adjustment of the pad in raised position comprising vertlcal teeth on said extensible connection, a pinion engaging said teeth and means for rotating said pinion, said Vertical teeth being long enough to retain engagement with the pinion during vertical movement of the sleeve, said sleeve raising means comprising a crank shaft journalled in the tubular member attached to the arm, with a block on a rod connected to a crank-pin of the crank shaft supporting the extensible connection.

FREDERIC BARNES WALDRON. 

